GNOME Bugzilla – Bug 144128
Can't relate size on screen to printed size
Last modified: 2009-01-31 19:44:39 UTC
This must surely be a problem with me, but I can't find anything in the documentation relating the size of objects in dia with the actual size when printing. What makes sense to me is that, at Zoom=100% in the main Dia window and Scale=1.0 in the Page Setup dialog box, what I print should be approximately the same size as what is on the screen. Instead, an object about 4 cm wide on the screen prints as an object less than 1 mm wide. Text sizes are also confusing. I can change the size of text by either entering a value for font size in the Properties: Standard - Text dialog box, or by clicking on the Font button, choosing Other fonts..., and selecting a font size. I assume that the font size in the Select font dialog box is in points, per usual practice, but then what does the font size mean in the Properties box? Is it a scaling factor? Setting it to 1.0 seems to produce things about the right size, so it looks like a scaling factor. I don't care whether it is scaling factor or a percentage scaling factor, but I don't know what it is. I assume that others are using Dia on a regular basis and would laugh at these silly questions, but I simply can't find the answer. Actually, other than this one problem, I really like Dia. I use its SVG export feature and adjust the size by trial and error and can then put it in my documentation.
At scale 1.0, what's 1cm logically (i.e. with respect to the grid lines and rulers) is 1cm on paper. However, since X in particular has had problems with getting the correct DPI for the screen, no serious effort has gone into making 1cm in the diagram = 1cm on the screen. The text size is, unfortunately, not in points, but in cm, which, too, is a known bug.
So, to verify what I think I understand about the various measures: 0. What You See Is Not Exactly What You Get, i.e. if the dots per inch on the screen is not 72, a Dia cm won't appear on the screen as 1 cm. Printers handle this correctly and 1 Dia cm = 1 cm on paper. 1. The unit of measurement on the rulers is centimeters. 2. The value of "Scale" in the "Page Setup" dialog box is in percentage. 3. The value of "Zoom" in the drawing window is also percentage. [Note: the default seems to be 5%, which is surprising] 4. In the "Diagram" menu item "Properties...", tab "Grid": a. The "Spacing" is in cm. b. "Visible spacing" is the number of gridlines between each visible grid line. 5. In the "Properties: Standard - Text" dialog for a text object: a. The "Font Size" item is measured in cm. b. If, in the "Font" item, you choose "Other fonts...", choosing a font size will make no difference in the display.
All correctly understood. Why it uses 5% for the default zoom I do not understand, though. I have started work towards having selectable units, separate for text and other lengths. Haven't gotten far enough to get it into 0.94 though.
The font widget now doesn't use the GTK selector anymore, so that problem has gone away. It is still a problem that screen size is not the same as print size at 100%, and I believe it is easier to get the correct DPI now.
given that I'm using Dia on screens of multiple sizes (5.6" .. 22" adapting my working distance) I would hate if 100% screen zoom would mean logical-cm == physical-cm - at least as default. Adding an option to still do so may be a future enhancement. IMO the current behaviour is just WYSIWYN ;)
now documented: 2009-01-31 Hans Breuer <hans@breuer.org> [ Huge documentation update from Mark Dexter, bug #455400, hope I didn't break anything during merge. ] * doc/en/*.xml doc/en/graphics/*.png : 1. major edits to the following XML files: usage-quickstart.xml, usage-canvas.xml, usage-objects.xml, usage-objects-basic.xml, usage-objects-special.xml, usage-objects-selecting.xml. Added documentation for items not previously documented (e.g., Diagram Tree, Sheets and Objects, etc.) and expanded other documentation. 2. Added 78 screenshots (for a total of 82). 3. Minor edit to authors.xml. (Still need to fix broken links and bad e-mails). 4. Updated images. These changes obsolete the following bugs: #347209, #439974, #144128.